1. Field of the Invention
The present invention relates in general to a paving apparatus, and relates in particular to an automatic steering control device for an asphalt finisher.
2. Technical Background
Efficient operation of an asphalt finisher is a key to high quality and cost effective construction of the roadway. The asphalt finisher (referred to as finisher hereinbelow) must be operated such that the asphalt is levelled quickly and accurately in accordance with the required design of the roadway. Proper steering of the finisher is a critical factor in achieving the efficient paving operation.
An automatic steering device known in the field, (for example in a Japanese Patent Application, Second Publication, H4-32883) comprises three photodetectors arranged on a side of the finisher to detect a reference line along the roadside, and the data are outputted to a controller. The controller monitors the current positions of the finisher with respect to the reference line periodically, and stores the respective current position data obtained at certain time intervals. The controller compares the current positional data with the previous positional data, and the steering direction is determined on the basis of the comparison data and the running period of the interval timer.
The above known arrangement presented a problem that there are only three detector devices provided for determining the travel direction of the finisher, it was not possible to display the details of the control process to monitor the progress of the actual paving operation. The accuracy of control was also not adequate.